After the Hurricane Katrina disaster in August, 2005 a massive influx of Latinos from Mexico and Central America, mostly men, undocumented and unaccompanied by their families, came seeking construction work. Post-disaster New Orleans is not only a new receiving area for Latino migrants, but an extremely high risk environment given its sex and drugs tourism which makes it a natural laboratory for the exploration of factors that promote drug use and HIV sexual risk among migrants. In October 2007, our research team assembled a cohort of 125 newly arrived Latino migrant workers (LMW) using respondent driven sampling, and followed them every 3 months to examine HIV risk. Over 9 months of follow-up, we discovered high rates of drug use ranging from 19% to 29% and 12 men who initiated drug use while in New Orleans and follow-up rates of 90%. From our preliminary data we know the "what", but we do not know the "why" and "how", which are the focus of this exploratory research. The overall goal of this research is to identify and explore factors affecting drug use and drug-related HIV sexual risk behaviors among Latino migrant workers who have migrated to a new receiving environment known for its sex and drugs tourism. The specific aims are: 1) To describe the patterns of drug use prospectively in a quasi-probability sample of 125 Latino workers migrating to a new high-risk U.S. receiving environment, 2) To explore the superstructural, structural, environmental, individual and cultural factors affecting initiation and continuation of drug use among Latino migrant workers using mixed methods and applying Sweat and Dennison's model of HIV causation and Handwerker's theory of culture as guides, 3) To describe the influence of drug use on HIV sexual risk behavior among Latino migrant workers, 4) To refine instrumentation and the theoretic framework to be used in further research on the relationship of drug use, migration, acculturation and HIV sexual risk behaviors. To achieve these aims, a multi-disciplinary team will employ mixed methods and continue to follow the cohort for an additional 18 months (for 30 months of total follow-up). Simultaneous qualitative and quantitative methods will be used to refine instrumentation and the theoretic framework and to explore factors associated with drug use and drug- related HIV sexual risk for a future R01 application. This is the only documented cohort to describe the evolution of drug use and HIV risk among migrant workers in a U.S. post-disaster setting where there are essentially no prevention or treatment services available. PUBLIC HEALTH RELEVANCE: Central America and Mexico, once thought to be areas with little drug use and low HIV prevalence, have seen a steady rise in rates. In these areas, the prevalence of HIV is higher in regions with significant emigration to the U.S. and there has been an explosion of migration to the U.S. by Mexicans and Central Americans. Close to 4 million Latin American migrants entered the U.S. between 1990 and 2000, doubling the number of foreign born Latinos in just a decade. Between 1990 and 2000, the number of Latinos in selected southern states that had no or small Latino populations in 1990 increased by more than 300% on average. New destinations are important because precipitators of acculturation-stress are likely to be greater than in more established areas. While many studies have described high rates of HIV risk behavior, far fewer have examined the broader context of this risk. This study will address this gap, as well as providing data from a high-risk behavior receiving environment in which the influence of extremes of drug use and sexual risk can help to illustrate factors affecting initiation, use patterns and drug-related sexual risk.